hibernate注解-屬性級別注解
來源：程序員人生 發(fā)布時間：2016-07-07 08:54:09 閱讀次數(shù)：3214次
屬性級別注解
添加方式：
寫在屬性字段上面
寫在屬性的get訪問器的上面
@Id
必須，定義了映照到數(shù)據(jù)庫表的主鍵的屬性，1個實(shí)體類可以有1個或多個屬性被映照為主鍵，
可置于主鍵屬性或getXxx()前，注意：如果有多個屬性定義為主鍵屬性，該實(shí)體類必須實(shí)現(xiàn)serializable接口
@SequenceGenerator
@GeneratedValue
@GeneratedValue(strategy=GenerationType,generator=""):可選，用于定義主鍵生成策略
strategy表示主鍵生成策略，取值有：
GenerationType.AUTO:根據(jù)底層數(shù)據(jù)庫自動選擇（默許）
GenerationType.INDENTITY:根據(jù)數(shù)據(jù)庫的Identity字段生成
GenerationType.SEQUENCE:使用Sequence來決定主鍵的取值
GenerationType.TABLE:使用指定表來決定主鍵取值，結(jié)合@TableGenerator使用
@Column
@Column-可將屬性映照到列，使用該注解來覆蓋默許值，@Column描寫了數(shù)據(jù)庫表中該字段的詳細(xì)定義，這對根據(jù)JPA
注解生成數(shù)據(jù)庫表結(jié)構(gòu)的工具非常有作用。
經(jīng)常使用屬性：
name:可選，表示數(shù)據(jù)庫表中該字段的名稱，默許情形屬性名稱1致
nullable:可選，表示該字段是不是允許為null,默許為true
unique:可選，表示該字段是不是為唯1標(biāo)識，默許為false
length:可選，表示該字段的大小，僅對String類型的字段有效，默許值225，主鍵不能使用默許值
insertable:可選，表示在ORM框架履行插入操作時，該字段是不是應(yīng)出現(xiàn)INSERTRT語句中，默許為true
updateable:可選，表示在ORM框架履行更新操作時，該字段是不是應(yīng)當(dāng)出現(xiàn)在UPDATE語句中，默許為true。對已創(chuàng)建
就不可以更改的字段，該屬性非常有用
@Embedded
@Embedded是注釋屬性的，表示該屬性的類是嵌入類。
注意：同時嵌入類也必須標(biāo)注@Embeddable注解
@EmbeddedId
@EmbeddedId使用嵌入式主鍵類實(shí)現(xiàn)復(fù)合主鍵
注意：嵌入式主鍵類必須實(shí)現(xiàn)Serializable接口、必須有默許的public無參數(shù)的構(gòu)造方法、必須覆蓋equals和hashCode方法
@Lob
@Version
@Basic
@Transient
可選，表示該屬性并不是1個到數(shù)據(jù)庫表的字段的映照，ORM框架將疏忽該屬性，如果1個屬性并不是數(shù)據(jù)庫表的字段映照，就
務(wù)勢必其標(biāo)示為@Transient，否則ORM框架默許其注解為@Basic
實(shí)例：
hibernate.properties配置：
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration⑶.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<!--
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///hibernate_struts_stumanager</property>
-->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mypage</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">root</property>
<property name="hibernate.show_sql">false</property>
<property name="hibernate.hbm2ddl.auto">create</property>
<!-- <property name="hibernate_current_session_context_class">thread</property> -->
<property name="current_session_context_class">thread</property>
<mapping class="com.entity.Students"/>
</session-factory>
</hibernate-configuration>
實(shí)體類Student：
package com.entity;
import java.io.Serializable;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;//JPA注解
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;
import org.hibernate.annotations.GenericGenerator;
/*
* 學(xué)生實(shí)體類
*/
//@Entity//
//@Entity(name="t_students")//如果不添加名字，則默許與實(shí)體類名字相同，如果想要自行設(shè)置表明，就需要自己進(jìn)行添加
@Entity
@Table(name="t_students1",schema="mypage")
public class Students implements Serializable{
@Id
// @GeneratedValue
// @GeneratedValue(strategy=GenerationType.AUTO)//與@GeneratedValue結(jié)果相同，字符串類型不能指定為AUTO類型
// private int sid; //學(xué)號
// @GeneratedValue(generator="sid")
// @GenericGenerator(name="sid",strategy="assigned")
// @Column(length=11)
// private String sid;
@EmbeddedId
private StudentPK pk;
// @Id
//
// @Column(length=11)
private String sname;//姓名
private String gender;//性別
private Date birthday;//誕生日期
private String major;//專業(yè)
private Address add;
@Transient //表示該字段不會被ORM映照到表里的字段
private double salary;//薪水
public Students(){
}
public Students(StudentPK pk, String sname, String gender,
Date date, String major,Address add,double salary) {
// super();
this.pk = pk;
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
this.add = add;
this.salary = salary;
}
public StudentPK getPk() {
return pk;
}
public void setPk(StudentPK pk) {
this.pk = pk;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getMajor() {
return major;
}
public void setMajor(String major) {
this.major = major;
}
public Address getAdd() {
return add;
}
public void setAdd(Address add) {
this.add = add;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
}
StudentPK實(shí)體類：
package com.entity;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Embeddable;
@Embeddable
public class StudentPK implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
@Column(length=18)
private String id;//身份證號
@Column(length=8)
private String sid;//學(xué)號
public StudentPK(){
}
public StudentPK(String id, String sid) {
this.id = id;
this.sid = sid;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getSid() {
return sid;
}
public void setSid(String sid) {
this.sid = sid;
}
@Override
public boolean equals(Object obj) {
// TODO Auto-generated method stub
return super.equals(obj);
}
@Override
public int hashCode() {
// TODO Auto-generated method stub
return super.hashCode();
}
}
地址類：
package com.entity;
import javax.persistence.Embeddable;
import javax.persistence.Embedded;
// 地址類
@Embeddable //表示是1個嵌入類，這個類的對象在另外一個實(shí)體類中充當(dāng)屬性
public class Address {
private String postCode;//郵編
private String address;//地址
private String phone;//聯(lián)系電話
public Address(){
}
public Address(String postCode, String address, String phone) {
this.postCode = postCode;
this.address = address;
this.phone = phone;
}
public String getPostCode() {
return postCode;
}
public void setPostCode(String postCode) {
this.postCode = postCode;
}
@Embedded
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
測試類：
package com.entity;
import java.util.Date;
import java.util.EnumSet;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;
public class TestStudents {
@Test
public void testShemaExport(){
//創(chuàng)建hibernate配置對象
Configuration config = new Configuration().configure();
//創(chuàng)建服務(wù)注冊對象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//創(chuàng)建hibernate配置對象
Configuration config = new Configuration().configure();
//創(chuàng)建服務(wù)注冊對象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//創(chuàng)建會話
Session session = sessionFactory.getCurrentSession();
//創(chuàng)建事務(wù)
Transaction tx = session.beginTransaction();
Address add = new Address("700005","河南理工大學(xué)","15039117115");
StudentPK pk = new StudentPK("012345678912345678","55555555");
Students s = new Students(pk,"張3豐","男",new Date(),"太極拳",add,7899);
session.save(s);
tx.commit();
// SchemaExport export = new SchemaExport(config);
// export.create(true,true);
}
}
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